Jonkershoek eddy covariance

Res, Sarah, Wataru & Zack

Intro

  • Data  
    • SAEON flux data from the eddy covariance system
    • Swartboschkloof, Jonkershoek
    • March 2022
  • Models
    • Random walk
    • Climatology (+ light & temp)
    • GAM

flux tower

Model Fitting

RandomWalk

model{

  #### Data Model
  for(t in 1:n){
    y[t] ~ dnorm(x[t],tau_obs)
  }

  #### Process Model
  for(t in 2:n){
    x[t]~dnorm(x[t-1],tau_add)
  }

  #### Priors
  x[1] ~ dnorm(x_ic,tau_ic)
  tau_obs ~ dgamma(a_obs,r_obs)
  tau_add ~ dgamma(a_add,r_add)
}

Climatology: Temp + Light

model{

  #### Data Model
  for(t in 1:n){
    y[t] ~ dnorm(x[t],tau_obs)
  }

  #### Process Model
  for(t in 2:n){
    x[t] <- rho * x[t-1] + b1 * light[t] + b2*temperature[t] + alpha[t-1]
  }

  #### Priors
  x[1] ~ dnorm(0,0.1)  # initial condition
  tau_obs ~ dgamma(1,1)  # observation error
  for (i in 1:(n-1)) {alpha[i] ~ dnorm(0,tau_add)}
  tau_add ~ dgamma(1,1) # process error
  rho ~ dunif(-1,1)  # autocorrelation
  b1 ~ dnorm(0,0.1) # coefficient for light
  b2 ~ dnorm(0,0.1)  # coefficient for temperature
}
"

Forecast

RandomWalk

Seasonality

Dynamic SS

Validation

RandomWalk

Seasonality

Dynamic SS
  X   N      MAE       MSE     RMSE Coverage_90
1 1 816 3.500486 23.596069 4.857579   1.0000000
2 1 816 1.514190  4.789437 2.188478   0.9642857
3 1 816 1.772113  6.601425 2.569324   0.9623016

Validation

Validation Day vs Night